Project Summary/Abstract Our overall goal is to determine the long-term consequences of chronic HIV/HCV coinfection as a result of injection drug use (IDU) and the impact of HCV cure on the relationship of liver fibrosis and immune activation/ dysregulation in reproductively aging HIV-infected women. Liver disease with accelerated liver fibrosis is a major cause of death in HIV/HCV coinfected adults. Global immune activation may partly explain this accelerated liver fibrosis. With the advent of interferon-free direct-acting antiviral agents (DAA), a decrease in the burden of liver disease is expected. It is unknown if, after HCV cure, HIV-associated immune dysfunction impacts liver fibrosis or if residual liver injury affects immune recovery in reproductively aging HIV/HCV-coinfected women. Estrogen depletion is associated with increased immune dysfunction and metabolic disruptions, including visceral obesity, which could impact liver fibrosis. HCV infection has a major impact on immunopathogenesis of HIV and HCV disease. Our studies show that coinfected women with liver disease as compared to coinfected women without liver disease, have increased activated CD4+ T cells, and changes in immune regulatory and maturational pathways critical for immune homeostasis, including regulatory (Treg), senescent, effector memory and effector T cells. Coinfected women also have higher levels of transforming growth factor-? (TGF-?), an immunosuppressive cytokine critical for Treg differentiation and an important regulator of liver inflammation and fibrosis, as well as IL- 7, which promotes HIV persistence, stimulates HIV replication and HIV reservoirs, and promotes fibrogenesis, compared to HIV-monoinfected women. Our central hypotheses are that after HCV cure, HIV/HCV- coinfected women, who are aging, will have impaired liver fibrosis regression, because of HIV- associated immune dysregulation and increased risk of metabolic perturbations including hepatic steatosis (or fatty liver). The specific aims are to: (1) Longitudinally examine the short and long-term effects of HIV and menopause on liver fibrosis after HCV cure in aging HIV/HCV-coinfected women and (2) Determine if liver fibrosis impacts immune activation and dysregulation after HCV cure in HIV/HCV-coinfected women. HCV- monoinfected, HIV-monoinfected and uninfected women will serve as controls. We plan to use medication, menopause, metabolic, and liver fibrosis data, and biorepository samples from the Women's Interagency HIV Study (WIHS), to accomplish our aims. State- of- the- art clinical and laboratory technologies will evaluate liver fibrosis and steatosis severity and gene-signature expression to elucidate pathways of immune activation and dysregulation assessed simultaneously with cellular phenotypic and soluble biomarkers. The WIHS provides a unique opportunity to tease out the complex contributions of HIV, HCV, liver injury and estrogen depletion on immunologic markers in women. The proposed studies will help us understand if estrogen depletion blunts recovery of liver injury after HCV cure and if residual liver injury affects HIV-associated immune activation/dysregulation. This will help inform strategies for prevention and treatment of liver fibrosis.